The present invention relates to a method for manufacturing a probe used in an electrical test of a device under test such as a semiconductor integrated circuit (hereinafter referred to as IC).
A plurality of ICs formed on a semiconductor wafer generally undergo an electrical test before being separated into respective chips to determine whether or not they are manufactured in accordance with the specification. The electrical test of this kind can be performed by using a probe assembly comprising a probe board and a plurality of probes attached to the probe board (e.g., refer to Patent Documents 1 and 2).
The probe of such a probe assembly is formed by using a silicon wafer as a base table, taking the flat form of the probe with a photosensitive photoresist on the base table by making use of a photolithographic technique, sequentially depositing metal materials in the recess on the base table formed by the resist to form the probe, and thereafter detaching the probe from the base table, as described in Patent Document 1.
To detach the probe from the silicon base table, an etching technique is utilized. For prevention of damage on the probe caused by the etching and easy detachment of the probe, a sacrificial layer made of a metal material such as copper different from the probe material is formed on the base table, and the probe material is deposited on the sacrificial layer. Thus, by removing the sacrificial layer by means of, for example, wet etching with etchant, the probe can be detached from the silicon base table.
However, when a plurality of micro probes formed collectively on the base table are soaked in the etchant until the sacrificial layer is completely removed, the plurality of micro probes may float on the etchant by the etching, in which case it is difficult to handle them.
Accordingly, it is preferable to finish the etching process in a state where the minimum and proper amount of sacrificial layer is left between the silicon base table and the probe required to achieve easy detachment of the probe and to hold the probe on the silicon base table.
After the etching process in which the proper amount of sacrificial layer is left, the probe can be detached by an external force with use of a tool such as a cutter knife or a spatula. However, if a large amount of sacrificial layer remains due to insufficiency of the etching process time, detachment of the probe attached to the silicon base table by the remaining large amount of sacrificial layer requires a strong force, and thus such a process may deform the probe.
For these reasons, it has been necessary to keep observing the etching process for detachment of the probe from the base table for a relatively long time so that the etching process may be performed appropriately, and the manufacturing process has been complicated in some cases. Thus, a novel manufacturing method that enables time reduction and simplification of the probe manufacturing process has been desired.
Patent Document 1: Japanese Patent Appln. Public Disclosure No. 2000-162241. Patent Document 2: International Publication WO2004/102207 Pamphlet.